An integrated circuit may include scan elements that provide for observation of, and control over, internal states within the integrated circuit. The scan elements may, for example, be used when testing and debugging the integrated circuit.
By way of example, a scan cell might be associated with a signal pin in order to capture data from and/or apply data to the integrated circuit. To provide for high observability and controllability, it may be desirable to have scan cells associated with many of the state elements in the integrated circuit. Moreover, it may be desirable to have each scan cell operate in a number of different modes. For example, a scan cell might be disabled (e.g., during normal operation of the integrated circuit), information in a scan cell might be stored into a state element, information in a state element might be loaded into a scan cell, and/or a scan cell input bit might be shifted into a scan cell output.